Denna rapport är resultatet av ett examensarbete på KTHs master-program för maskinkonstruktion i samarbete med Atlas Copco och Svea Teknik. Atlas Copco utvecklar en tunnelborrningsmaskin som trycker sig framåt och glider på skidor under borrning. Detta har visats sig ge stora friktionsförluster mellan det ojämna gruvgolvet och skidan vilket gör att de behöver en alternativ lösning på detta problem som klarar lasterna från borrning och maskinens egenvikt samt reducerar friktionen i maskinens längdriktning. Konceptutvecklingen var indelad i fyra stora delsteg: konceptgenerering, val av koncept, vidareutveckling och analys och utvärdering. Projektet avser endast konceptutveckling, ingen fullständig konstruktion. Några komponenter kunde bli omkonstruerade av Atlas Copco vid behov, de främre stingrarna som håller den stabil mot taket fick inte ändras, inga ritningar ritades, ingen detaljerad FEM-modellering och inte alla externa komponenter blev valda. Två koncept togs till vidareutveckling genom Pughs beslutsmatris: The Slide Guide och The Rocker Bogie. CAD modeller ritades och blev analyserade med avseende på strukturella laster och friktionskoefficienter jämfört med den befintliga lösningen. The Slide Guide klarar alla krav som kunde jämföras och The Rocker Bogie klarade inte utrymmeskraven och skulle kräva omfattande omkonstruktion av main body för att fungera. Koncepten blev utvärderade med hjälp av olika beräkningar och FEM analys / This report is the result of a master thesis at KTH Machine Design in cooperation with Atlas Copco and Svea Teknik. Atlas Copco is developing a Tunnel Boring Machine that pushes itself forward on steel skids using a torque tube when boring. This has proven to suffer from large frictional forces between the rough mine floor and the skid and they need an alternative solution to hold the loads of the machine while boring and reducing the friction when propelling itself forward. The concept development was divided into four main stages, concept generation, concept selection, further development, analysis and evaluation. The project includes only concept development, no complete designs. Some parts could be redesigned by Atlas Copco if needed, the front stingers supporting against the roof was not to be redesigned, no drawings was made, no detailed FEA modeling was done and not all external components was chosen. Two concepts where chosen for further development using the PUGH’s decision matrix, The Slide Guide and The Rocker Bogie. CAD models was developed and analyzed regarding loads and friction compared to the existing solution. The Slide Guide clears all requirements that could be measured and the Rocker Bogie does not fit within the geometrical limits available without extensive redesign of the Main Body. This was verified using calculations and structural FEA.

Biological sulphate reduction (BSR) has been identified as a promising alternative technology for the treatment of acid mine drainage. BSR is a process that uses sulphate reducing bacteria to reduce sulphate to sulphide using substrates as nutrients under anaerobic conditions. The performance of BSR is dependent on several factors including substrate, pH, temperature and hydraulic retention time (HRT). In a quest to find a cost effective technology, Mintek conducted bench-scale tests on BSR that led to the commissioning of a pilot plant at a coal mine in Mpumalanga province, South Africa. This current study forms part of the ongoing tests that are conducted to improve Mintek’s process. The purpose of this study was to investigate the robustness of Mintek’s process and to develop a tool that can be used to predict the process’ performance with varying pH, temperature and HRT. Design Expert version 11.1.2.0 was used to design the experiments using the Box-Behnken design. In the design, pH ranged from 4 to 6, temperature from 10 °C to 30 °C and HRT from 2 d to 7 d with sulphate reduction efficiency, sulphate reduction rate and sulphide production as response variables. Experiments were carried out in water jacketed packed bed reactors that were operated in a down-flow mode. The reactors were packed with woodchips, wood shaving, hay, lucerne straw and cow manure as support for sulphate reducing bacteria (SRB) biofilm. Cow manure and lucerne pellets were used as the main substrates and they were replenished once a week. These reactors mimicked the pilot plant. The data obtained were statistically analysed using response surface methodology. The results showed that pH did not have a significant impact on the responses (p>0.05). Temperature and HRT, on the other hand, greatly impacted the process (p<0.05) and the interaction between these two factors was found to be strong. Sulphate reduction efficiency and sulphate reduction rate decreased by over 60 % with a decrease in temperature 30 °C to 10 °C. Generally, a decrease in sulphide production was observed with a decrease in temperature. Overall, a decrease in HRT resulted in a decline of sulphate reduction efficiency and sulphide production but favoured sulphate reduction rate. This study demonstrated that Mintek’s process can be operated at pH as low as 4 without any significant impact on the performance. This decreases the lime requirements and sludge production during the pre-neutralisation stage by close to 50 %. There was, however, a strong interaction between temperature and HRT which can be used to improve the performance especially during the winter season. / Dissertation (MEng)--University of Pretoria, 2020. / Chemical Engineering / MEng / Unrestricted

No description available.

Le mercure est un polluant ubiquiste dont les espèces organiques, telles que le méthylmercure (MMHg), s'accumulent dans la chaîne trophique et sont fortement toxiques pour les organismes vivants. Des microorganismes anaérobies sont capables de transformer le mercure inorganique en MMHg, et inversement, par des processus qui n’ont pas été complètement établis. Cette étude vise à mieux comprendre les transformations du mercure chez des bactéries sulfato-réductrices modèles : D. dechloracetivorans BerOc1, capable de méthyler et déméthyler le mercure, et D. desulfuricans G200, utilisé ici comme témoin non méthylant. Les objectifs de cette étude sont donc de déterminer où ont lieu les processus de méthylation et déméthylation du mercure à l’échelle cellulaire ainsi que d’identifier les ligands du mercure impliqués dans ces processus. Dans un premier temps, la toxicité du mercure inorganique (IHg) et du MMHg a été évaluée sur la croissance des deux souches. Les potentiels de méthylation et de déméthylation, la localisation du mercure et ses ligands ont été déterminés au niveau de la culture et à l’échelle cellulaire. Ces paramètres ont été évalués à différentes concentrations de mercure ainsi qu’au cours d’une cinétique. Ce travail de thèse a mis en avant que IHg et MMHg ont moins d’impact sur la croissance des deux souches étudiées en sulfato-réduction du fait de la forte précipitation du mercure. Une ou des étapes limitantes interviendraient dans le processus de méthylation. De plus, une différence de localisation cellulaire du mercure a été constatée au cours du temps, suggérant un export de ce dernier, et selon la souche bactérienne suggérant des mécanismes cellulaires différents. L’imagerie par TEM EDX et l’analyse élémentaire par nano-fluorescence X ont permis d’observer la co-localisation du mercure avec le soufre. L‘étude de la spéciation par HR XANES a confirmé la prédominance de ligands thiols associés aux processus de méthylation et de déméthylation. Une forme tétragonale est prédominante dans les échantillons exposés à HgCl2 en croissance suggérant que cette espèce est formée via un processus biologique. / Mercury is a wide spread pollutant that build up in living tissues. The transformation of mercury into methylmercury is primarily a natural and biological process mediated by anaerobic bacteria. Understanding the parameters influencing the formation of methylmercury is critically important due to its highly toxic, bioaccumulative and persistent nature. Herein we aim to study the mechanism by which model strains used in laboratories can transform inorganic and methylmercury. The objectives of this study are determining where mercury methylation and demethylation processes take place at the cell scale and identifying the mercury ligands involved in these processes. At first, the toxicity of inorganic mercury (IHg) and MMHg were measured on the bacterial growth. The methylation and demethylation potentials, the localization of mercury and its ligands were determined in the culture and at the cell scale. These parameters were evaluated at different concentrations of mercury as well as during kinetic. This study has highlighted that IHg and MMHg have less impact on the growth of both strains in sulfate reduction because of the high precipitation of mercury. One or more limiting steps would occur in the methylation process. In addition, a difference in cell localization of mercury has been observed over time, suggesting an export at 24h of exposure. Mercury localization also depends on the bacterial strain suggesting different cell mechanisms. TEM EDX imaging and elemental analysis by X-ray nano-fluorescence showed mercury co-localized with sulfur. The study of HR XANES speciation confirmed the predominance of thiol ligands associated with methylation and demethylation processes. A tetragonal form is predominant in samples exposed to growing HgCl2 suggesting that this species is formed via a biological process.

Approximately 55% of intensive care unit (ICU) patients require the use of a central venous catheter (CVC). CVCs are often an essential component of care; however, CVCs can create avenues for pathogens to enter the bloodstream and cause a central line-associated bloodstream infections (CLABSI), which can lead to increased mortality and morbidity, prolonged length of stay, increased cost of care, decreased patient satisfaction, and increased workload. In 2017, the CLABSI rate at the project site was 4.3 per 1,000 catheter days as compared to the national rate of 0.8 per 1,000 catheter days. Based on Piaget's theory of constructivism, a simulation-based staff educational program was developed and implemented by ICU staff (n=20). Following the implementation of the simulation-based program, adherence to CVC maintenance guidelines improved from 41.5% to 87.9%. A sample t-test showed that this improvement was statistically significant and the CLABSI rate declined to 1.24 per 1,000 catheter days in the 4-week period following implementation of the program. Findings show that introducing a simulation-based training program might help to reduce CLABSI rates in the ICU setting and contribute to positive social change by improving health outcomes in ICU patients with a CVC.

Iron is a common cation in biomineral sand; it is present for example in magnetite produced by magnetotactic bacteria and in iron sulfides produced by sulfate reducing microorganisms. The work presented in this thesis focused on two types of microorganisms capable of forming iron biominerals. In the first project I have studied the effect of O2 on the respiratory physiology and the formation of magnetosomes by Magnetospirillum magneticum AMB-1. In the second project I have studied the relationship between olivine and the activity of dissimilatory sulfate reducing (DSR) microorganisms. For the first project, I grew cells of AMB-1 in cultures with various concentrations of O2 and monitored growth and the formation of magnetic mineral particles (MMP). Results have shown that AMB-1 cells grew better at 100-225 uMO2(aq) than at lower [O2], yet the formation of MMP was repressed at ~45 uM O2(aq) and strongly inhibited at >100 uM O2(aq).These results have helped better understand the dissimilarity between the optimal growth conditions of magnetotactic bacteria and the conditions needed for the formation of MMPs. My results have also shown that the reaction between H2S produced by DSRs and olivine is abiotic, not catalyzed and exergonic. The pH did not vary significantly during this reaction and pH variation (in the 5-9 range) did not significantly influence this chemical reaction. Bicarbonate inhibited the reaction between H2S and olivine, but not the chemical equilibrium. Phosphate, a weak iron chelator, influenced the equilibrium of the reaction and it is assumed to help increase the rate of olivine weathering in the presence of DSRs. The activity of DSRs was positively influenced by the presence and abundance of olivine. Based on my results I propose that olivine help DSR obtain energy more efficiently, but does not represent a source of energy or nutrients for the cells. These results helped better understand the formation of iron biominerals and signatures of this activity.

This diploma thesis studies the utilization of whey using thermophilic bacteria of the genus Thermus and Geobacillus. The whey stripped off proteins was used as a cultivation medium during experiments. The cultivation took place in the Erlenmeyer flasks, to assess the optimal conditions for microrganism’s growth. During the cultivation in the bioreactor, growth curves were established. The amount of whey utilization was assessed by analytical methods that determine the concentration of reducing saccharides (lactose) and chemical oxygen demand (COD) while studying the optimal conditions and a method determining the concentration of reducing saccharides during growth curves analysis.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19733号 / 工博第4188号 / 新制||工||1646(附属図書館) / 32769 / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 辻 康之, 教授 大江 浩一, 教授 中村 正治 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

No description available.

Lactose is the common disaccharide found in dairy products. It can, however, be a source of discomfort for those whom are lactose intolerant. Therefore, it is necessary to accurately, reliably, and efficiently determine the lactose content of foods. The goal of this research was to develop a reversed-phase HPLC method with UV detection for the determination of lactose. Aminobenzoic acid was used to prepare a derivative, making detection possible in the 300-360 nm region. The stationary phase is a C8 column, with 85% methanol 15% water mixture at pH 5 as the mobile phase. A linear response of peak area to lactose concentration of 0.018 mg/mL to 0.36 mg/mL was obtained with an estimated detection limit of 0.0036 mg/mL lactose concentration. The reproducibility was established with a 4.95% relative standard deviation. The average recovery was 107%, and results were in strong agreement with the standard alkaline ferricyanide method, establishing accuracy.